1. Field of Invention
The present invention relates principally to hazardous waste containment systems and more particularly to a method for preventing the migration and leaching of hazardous fluid substances into the water table, and apparatus used in conjunction therewith.
The present invention teaches an apparatus for providing a containment wall comprising a plurality of slidingly engaged, interlocked vertical barrier members. The barrier members are engaged via interlocking connectors, which include therein a means for forming a fluid impermeable seal.
The preferred method for implementing the invention includes the preparation of vertical openings of prescribed depth, width, and/or diameter in the soil surrounding the area to be contained, installation of the vertical barrier or containment wall, and engaging sealant means, filling cores of the barrier members, and backfilling.
The present invention may be used to restrain the lateral migration of a variety of materials, both liquid and gas, and may be implemented in various soil conditions with similarly successful results.
The system of the present invention provides an efficient and cost effective containment system, as will be shown infra.
An alternative embodiment of the method of the present invention includes the engagement of the barrier members and welding of the interlocked connection at the joint formed by the mating interlocking parts to facilitate greater structural integrity and a greater sealing capability.
Another alternative method of installing the present system includes the utilization of a guide box template/anti-caving system for properly aligning the barrier members and provides a means of installation where soil conditions are such that there is a likelihood for cave in.
2. Prior Art & General Background
As may be determined by a review of the below cited patents, the prior art has failed to contemplate a system as taught in the present invention. Further, the patents cited below are fully distinguishable in construction and use, and are cited only as being at best remotely pertinent to the claimed invention.
A list of prior patents which may be of interest is presented below:
______________________________________ Patent No. Patentee(s) Issue Data ______________________________________ 2,101,285 Stevens 12/07/1937 2,937,065 L. Harza 05/17/1960 2,961,731 Buzzell et al. 11/29/1960 3,202,412 Hunsucker 02/07/1967 3,411,305 A. Cella 11/19/1968 3,848,855 Weiland 11/19/1974 3,886,705 Cornland 06/03/1975 4,808,039 Fischer 02/28/1989 ______________________________________
A cursory review of the above cited patents shows that the prior art is indeed distinguishable from the present invention. Indeed most, if not all, of the cited patents are not part of the prior art of the invention but rather are from disparate, nonanalogous arts.
U.S. Pat. No. 2,101,285 teaches a "tubular interlocking piling" of steel having interlocking structures incorporated therewith. The specification teaches the system as being used in the construction or reinforcement of coffer dams, bridge piers and the like. It is noted that the apparatus does not contemplate the utilization of a containment structure, although it does teach implementation as a support wall for above ground construction. Further, unlike the present invention, sealing means for preventing fluid migration is not taught.
U.S. Pat. No. 3,302,412 to Hunsucker teaches "interlocking sheet piles and method of installation", including means to slidingly engage and seal the sheet piles. This system is likewise obviously distinguishable from the present invention, for a variety of reasons. The '412 patent is directed to sheet pilings for forming earthen walls or cofferdams, and is not directed to containment systems, as discussed in the present invention. Further, implementation of the system is impractical, very costly and would be highly unsuitable for use in the types of soil conditions anticipated by the system of the present invention.
For example, the scraper 24 (FIG. 3) is inadequate to remove debris from the cavity 16 while the sheet pile is being driven into the soil. The "scraped" debris would not have anywhere to go, as the tolerance of the shoe and cavity connection is too little to be expected therethrough and the debris could not be pushed through the bottom of the cavity as it is already firmly embedded in packed soil.
While the tolerance of the engagement system is too small to allow scraping of debris therethrough, it is of sufficient tolerance that it allows liberal leakage of a fluid sealant, to the point that it would be impossible to accurately project a fluid impermeable seal on a consistently monitorable basis.
The lugs 30 (FIG. 2) as taught in '412 render the system unworkable in terms of taking away the tolerance necessary for slidingly engaging the panels. The tolerance or gap between the shoe and cavity is needed to allow a smooth installation. Lastly, the construction is overly costly and highly impractical, with the necessity of multiple apertures to be fabricated therein, the alignment of apertures to both cavities, the removal and replacement of the feed tube at each driven pile, and the implementation of scrapers as taught in the specification in the field would be very difficult and time consuming. Thus, even if the system works as taught, it would be usable only with extreme cost and complexity of fabrication.
U.S. Pat. No. 3,886,705 to Cornland teaches a "Hollow Structural Panel of Extruded Plastics Material and a Composite Panel Structure Formed Thereof". The patent teaches a hollow structural panel configured to form partition walls or the like and is designed for resisting deformation due to load bearing. While '705 does teach the utilization of a rubber gasket for preventing leakage of snow, rain, or the like, this apparatus is unsuitable for utilization in conjunction with the system of the present invention. Apparently, the system of '705 would require complete fabrication above ground prior to installation, which would make the system unsuitable for use with the preferred method of the present invention.
U.S. Pat. No. 3,411,305 issued 1968 to Cella teaches a "Tubular Interlocking Piling for Wall Assemblies". A variation of sheet piling technology, this patent contemplates a system of interlocking piling components in the construction of "cofferdams, walls, dams, piers, abutments, and other types of walls where strong construction is necessary."
The '305 disclosure teaches the "tubular pile unit" of a sufficiently strong material for forming a substantial load bearing wall; it is noted that the disclosure does not teach in any manner a fluid impermeable unit. Consequently, this apparatus is likewise unsuitable for the preferred system contemplated in the present invention. Further, it is noted that load bearing is not a factor in the present invention, for which factor the '305 patent is primarily designed.
U.S. Pat. Nos. 2,937,065 and 2,961,731 teach fluid impermeable gasket systems fully distinguishable in use, method and apparatus from the present invention.
Not found during the patent search, but known to applicant, is an apparently unpatented method for containing hazardous waste. This present method of preventing the leaching of contaminated fluids from hazardous waste sites comprises the implementation of a "slurry" wall around the site. A trench is dug to a sufficient depth to contact a fluid impermeable natural earth strata, such as clay.
A problem with preparing such a trench, however, relates to the soils' cohesive strength and its propensity for "caving." This system therefore often has had to resort to expensive sheet pilings to retain and strengthen the trench walls. As the sheet pilings typically were insufficient to prevent seepage of the containment therethrough, a still more expensive medium, typically bentonite, a naturally occurring clay, was used to fill the trench. This slurry would solidify, forming a fluid impermeable subterranean "dam" for containment.
The present invention is anticipated to cost substantially less than the most cost efficient slurry wall system as it will not require sheet pilings or any other means of preventing "caving" as such means is inherent in the present system.
Other material costs of the present system are likewise significantly less, requiring as little as one-one-hundredth (1/100) of the amount of bentonite. It is noted that the bentonite costs fluctuate, but may run as high as $200.00 per ton including freight (freight on board) job site.
Likewise, the present invention does not require the utilization of piling equipment, heavy lift equipment, or extensive labor, as is necessary for implementation of the above system.
3. General, Summary Discussion of the Invention
The present invention overcomes the problems of the prior art by providing a system which is reliable, relatively economical and less hazardous.
As may be noted above, the prior art does not contemplate a relatively inexpensive yet consistently impermeable, readily implemented containment system for preventing the leaching of toxic materials from dump sites and the like.
The only method vaguely pertinent to the present invention relates to an expensive process requiring heavy machinery and costly materials; namely, the method of providing slurry wall systems having sheet pile walls.
The exemplary embodiment of the present system comprises the utilization of a plurality of barrier members, each barrier member having an extruded tubular body structure with appendages on the exterior wall at a hundred and eighty (180) degree separation from each other. The appendages are of a "male" and "female" type, respectively, and are configured to slidingly engage the barrier members longitudinally in vertical fashion.
Further, the appendages are configured with each having a slot to form a vertical, self-aligning void or chamber when they are slidingly mated with the associated appendage of another member. This vertical chamber may then be filled with a sealant to prevent leaching of migrating substances out of the containment area into the surrounding areas and thence into the ground water.
It is noted that the appendages are not limited to a hundred and eighty (180) degree separation and may be implemented in a variety of circumferentially located positions relative to the other. For example, a ninety (90) degree separation would be used for a "corner" barrier member, while a variety of other degree separations could be utilized to form a "kidney" configured containment area. Other degree separations may be utilized for forming still other geometric containment configurations. Thus, the containment system need not necessarily form a circle or rectangle, and may be configured to contain any desired layout. It is noted that the engagement appendages for all configuration barrier members are designed to mate with the appendage of other members of this invention.
The present invention of providing a vertical wall as a containment barrier is possible as the wall is implemented to a depth to intersect the clay strata in the soil, a fluid impermeable strata found at varying depths. Thus, various sites require different depths of implementation utilizing differing member lengths. Normally it is not necessary to go deeper than forty (40') feet, and, thus, conventional excavation equipment tools may be used in the present system. It is noted that clay is not the only fluid impermeable strata, and the present system may be used in conjunction with other fluid impermeable strata as well with satisfactory results.
Another step, when desirable, in the method of the present invention is the implementation of a sealing media to embed the base of the containment wall to prevent leaching thereunder.
The exemplary embodiment of this step utilizes, when desirable, the naturally occurring clay bentonite as taught in the slurry wall concept for the base sealant, but in far less amounts. The base sealant need be implemented only in an amount sufficient to embed the intersection of the wall and the strata. This may be, for example, four (4") inches. It is noted that, in some situations, this step may not be necessary.
The present system teaches an alternate or supplemental step for use where greater structural integrity of the barrier wall and/or higher sealing properties are desirable. This additional step comprises the welding of the engagement joint in the areas within the sealant chamber prior to injection of the sealant. The welding of the engagement area is performed utilizing a specially designed welding probe, which is lowered into the chamber after the barrier members have been slidingly engaged. Once the weld is complete, a sealant will be deposited or injected into the remaining void.
For installation of the present invention in soil conditions having a likelihood of "caving", the present invention teaches the implementation of a "guide box" template system extending the full depth of the excavation. The "guide box" serves five apparent purposes, to wit: 1) it provides a support structure which will restrain any caving walls of the excavation from entering the area where the members are to be installed, lessening the likelihood of complications during engagement of the barrier members; 2) it provides a template for easy engagement and proper alignment of the barrier members during installation; 3) it provides protection for previously installed members against damage from the auger (when an augured hole is desirable); 4) it acts as a guide for the auger; and 5) it can allow for gradual and controlled backfilling by being slowly extracted.
The present system contemplates excavation of the ground soil via trenching or auguring, but expressly teaches that other methods of excavation may be utilized with satisfactory results.
It is therefore an object of the present invention to provide a system for containing hazardous wastes, which is efficient, utilitarian, and cost effective, and which provides reliable protection against the threat of migrating contamination of adjacent aquifers and soil.
It is a further object of the present invention to provide a system for containing hazardous wastes, which utilizes a plurality of smilingly engaged interlocking containment members.
It is a still further object of the present invention to provide a system for containing hazardous wastes that is adaptable to a variety of dump site configurations.
It is another object of the present invention to provide a system for containing hazardous wastes which provides reliable containment for a period of time equal to or exceeding convenient methods.
It is another object of the present invention to provide a system for containing hazardous wastes until such time as it can be removed or neutralized as desired.
It is still another object of the present invention to provide a method of sealing slidingly engaged vertical barrier members, including the step of welding the engaged area via a specially designed welding probe lowered into the sealant chamber.
It is a further object of the present invention to provide a method of installing a hazardous waste containment system utilizing a plurality of vertical barrier members wherein the method includes the utilization of a "guide box" template which aids in the installation process.